The invention relates to percussive musical instruments. Such instruments include but are not limited to bells, chimes, gongs, glockenspiels, xylophones, harps, drums, and the like. The invention is especially concerned with the playing of these instruments by electrically actuated means. In all of these instruments, sound is produced as the result of the action between a striker, or clapper, and a struck object. In a bell, for example, the object struck is a bell and the striker is a clapper; in a xylophone, the object struck is a tuned wooden bar, and the striker is a mallet; in a drum, the object struck is a drum, and the striker is a drum stick. The one thing common to all is that, in order to produce a sound, it is necessary to accelerate a mass sufficiently that when this mass strikes the struck object, the desired sound will be produced. The loudness of the sound will depend, among other things, on the speed of travel of the armature.
It should be noted that in all cases, the object struck, which may be referred to as the instrument, has the qualities of hardness and elasticity. Therefore, when the clapper strikes the instrument, the interaction which takes place will cause the clapper to be accelerated in the opposite direction. This acceleration in the direction opposite to strike is sometimes referred to as the rebound. In prior electrically actuated percussive instruments, control of the rebound has proved to be very troublesome.
Perhaps the most common and well-known type of electrically controlled striker has been that used in door chimes where the clapper consists of a moveable iron core which forms the armature core of an electrical solenoid. The armature core is held by a spring in a rest position that is off center of the solenoid. When the solenoid coil is energized, the armature core will be drawn toward the center of the solenoid; however, because of the fact that such a core is a mass which is accelerated by such an action, the stored energy will cause it to overtravel the center and strike the chime tube. Having struck the chime tube, the armature will rebound and then oscillate due to the spring and to the fact that such a system provides poor means for damping such vibration. Another drawback of such a system is the fact that, since the armature moves within the solenoid, it moves in an environment where parts rub against each other. Such friction produces undesirable noise and reduces efficiency. Another element of such a system which reduces efficiency is the fact that energy is required to overcome the force applied to the armature by the action of the spring. While other devices, such as pneumatic systems, have been employed to actuate strikers, they have all suffered from similar problems.
Another drawback of prior electrically operated systems has been the fact that sometimes the force of the solenoid holds the striker against the object struck so that it does not immediately rebound, thereby producing a very poor or damped sound.
Besides the problems of inefficiency and noise have been the drawbacks from the standpoint of the musician. Prior solenoid type devices have been subject to corrosion, accumulation of dirt, or the like, which can change the frictional characteristics of the solenoid and produce erratic, unpredictable action, both as to the timing of the armature motion after energization of the solenoid and the force of the striking motion. Thus, there is poor sound regulation with such devices, especially when soft sounds are desired. Some devices don't work at all without regular cleaning and adjustment. Further, because of the lack of damping of the oscillation or vibration on the rebound, as well as the friction inherent in the systems, it has, until the present invention, been impossible for the performer to repeat notes rapidly and each time secure the desired loudness. From the standpoint of the musician, this has been very undesirable.